Description (adapted from the Abstract): The overall objective of this project is to develop and apply mathematical models to design control strategies that will reduce morbidity and mortality while simultaneously reducing the impact of drug resistance when controlling epidemics of the human immunodeficiency virus (HIV), Mycobacterium tuberculosis (TB), and herpes simplex virus-2 (HSV-2). The project brings together a community of researchers that includes both mathematical modelers and infectious disease experts. The aims are to (1) formulate a series of disease specific mathematical models that reflect the transmission dynamics of drug-sensitive and drug-resistant pathogens in a treated population, (2) (a) predict incidence and prevalence of drug resistance, and (b) identify which biological, behavioral, or treatment factor are most important in contributing to the emergence and transmission of drug resistance,, and (3) (a) design control strategies, (b) develop evaluation criteria, and 8 use the criteria to evaluate tradeoffs among medical and behavioral interventions when designing and improving control strategies. HIV control strategies will be designed for HIV-infected gay communities in which combination therapies are used, as well as vaccines. TV control strategies are based on vaccinations, chemoprophylaxis, chronic suppression, and potential vaccines. The researchers will also consider the potential effects if the HIV epidemic on causing increased morbidity, mortality, and levels of drug resistance to both TV and HSV-2.